Fundamental WiMAX Concepts

  WiMAX has four fundamental architectural components:

Base Station (BS) : 

      The BS is the node that logically connects wireless subscriber devices to operator networks. The BS maintains communications with subscriber devices and governs access to the operator networks. A BS consists of the infrastructure elements necessary to enable wireless communications, i.e., antennas, transceivers, and other electromagnetic wave transmitting equipment.

      BSs are typically fixed nodes, but they may also be used as part of mobile solutions , for example, a BS may be affixed to a vehicle to provide communications for nearby WiMAX devices. A BS also serves as a Master Relay-Base Station in the multi-hop relay topology .


Subscriber Station (SS) : 

     The SS is a fixed wireless node. An SS typically communicates only with BSs, except for multi-hop relay network operations . SSs are available in both outdoor and indoor models.

Mobile Subscriber (MS) : 

     Defined in IEEE 802.16e-2005, MSs are wireless nodes that work at vehicular speeds and support enhanced power management modes of operation. MS devices are typically small and self-powered, e.g., laptops, cellular phones, and other portable electronic devices.

Relay Station (RS) : 

     Defined in IEEE 802.16j-2009, RSs are SSs configured to forward traffic to other RSs, SSs, or MSs in a multi-hop Security Zone.





     WiMAX devices communicate using two message types:
 
                                                --> Management messages
                                                --> Data messages.

     Data messages transport data across the WiMAX network.
     Management messages are used to maintain communications between an SS/MS and BS, i.e., establishing communication parameters, exchanging security settings, and performing system registration events (initial network entry, handoffs, etc.) .